Stop motion device for flat knitting machines

ABSTRACT

A thread delivery and control device for a flat weft knitting machine having a machine drive which can be switched off by the control device. A thread storage device is positioned between the bobbin and the thread processing parts of the machine, and a stop motion device is located between the bobbin and thread storage device. A signal transmitter, as controlled by the machine, occupies one of two control positions when the machine is in given recurrent positions in which idling of the machine has little or no disadvantageous effect. A coincidence circuit connects the stop motion device and signal transmitter to the control device.

United States Patent [191 Rosen STOP MOTION DEVICE FOR FLAT KNITTINGMACHINES Inventor: Karl Isac Joel Rosen, Villa Haya,

S-523 00, Ulricehamn, Sweden Filed: June 7, 1972 Appl. No.: 260,361

Foreign Application Priority Data June 8, 1971 Germany 2128476 US. Cl.66/163 Int. Cl D04b 35/14 Field of Search 66/ 163 References CitedUNITED STATES PATENTS 3/1888 Talcott .1 66/163 FOREIGN PATENTS ORAPPLlCATIONS 3/1949 Great Britain 66/163 Apr. 30, 1974 PrimaryExaminer-Robert R. Mackey Attorney, Agent, or Firm-Woodhams, Blanchard &

Flynn [57] ABSTRACT A thread delivery and control device for a flat weftknitting machine having a machine drive which can be switched off by thecontrol device. A thread storage device is positioned between the bobbinand the thread processing parts of the machine, and a stop motion deviceis located between the bobbin and thread storage device. A signaltransmitter, as controlled by the machine, occupies one of two controlpositions when the machine is in given recurrent positions in whichidling of the machine has little or no disadvantageous effect. Acoincidence circuit connects the stop motion device and signaltransmitter to the control device.

6 Claims, 4 Drawing Figures PAIENTEDAPR 30 1914 3.807L199 SHLEI 1 (If 3PATENTEDAPR 30 1914 3.807; 199

SHEET 2 [IF 3 Fig. 2

PATENIEOAPNOIHM 3l807l199 SHEEI 3 OF 3 STOP MOTION DEVICE FOR FLATKNITTING MABHINES The invention relates to a thread delivery and controldevice on flat weft knitting machines (Cotton machines) and similarmachines, such as flat machines and Raschel machines, having a drivewhich can be turned off by a switch device.

A considerable number of defects in articles manufactured by the saidknitting machines are caused by thread breakages during delivery. Such athread breakage is often not discovered until the produced thread end isalready knitted into thearticle. In the caseof flat weft knittingmachines theresult is that the knitted article is severed from theneedles. In this case the quantity of thread which is processedincorrectly in this manner is lost. In addition, the flaw must besubjectedto additional treatment which is time consuming. For example,in a machine having a plurality of knitting systems, that knittingsystem on which a thread breakage has been detected must be correctedwhile the other knitting systems are inoperative until paralleloperationis restored.

Even if a thread breakage is discovered before the produced thread endis worked into the knitted article, this can cause flaws in the knittedarticle. If the slide feeding the thread is stopped on its path betweenthe two points of reversal, there occurs a change in the tension of thedelivered thread which is manifested in irregularity in the manufacturedarticle.

The problem underlying the invention is to provide a thread delivery andcontrol device for'the said knitting machines, whereby a fluent mode ofoperation is made possible and whereby the described irregularities inthe knitted article are prevented by'stopping the sliding carriage intheevent of a thread breakage.

This problem is solved in accordance with the invention by a basicallyknown storage means between the thread supply bobbin and the threadprocessing parts of the machine, a stop motion device between saidbobbin and storage means, a signal generator which can be controlled bythe machine and occupies one of two switch positions when the machine isin certain recurrent positions in which idling of the machine has littleor no disadvantageous effect, and a coincidence circuit by which thestop mo'tion device and signal generator are connected to the switchdevice.

The invention is basedon the theory that in the case of the saidknitting machines there are periodic time intervals during motion inwhich an idling machine does not have a disadvantageous effect on theknitted article. While, for example, in the case of a flat weft knitting.machine stopping of the machine during weft knitting has a particularlydisadvantageous effect, stopping during application and cutting of thethread does not interfere with the process. The same applies to flatmachines with which it is considerably more advantageous to stop thesliding carriage at one of its reversal points and not between them. Theuse of a thread'storage means makes it possible for the machine tocontinue moving as faras one of these points. On the storage devicethere must be at least a'quantity of thread so that, after a threadbreakage is detected, there is sufficient thread available so that themachine can continue moving until it reaches one of the said selectedpoints. In this connection control of the machine is effected asfollows. A signal is given by the stop motion device whenever a threadbreakage is detected. The signal generator gives a periodic sequence ofsignals whenever the machine is in an interval of movement in which itcan easily be rendered inoperative. The drive of the machine is onlyswitched off by the coincidence circuit and the provided control devicewhen a thread breakage has been detected and the machine is located inone of these intervals of movement In practice it seems that after athread breakage the machine continues moving until it is located in aninterval of movement in which it may be switched off and then renderedinoperative, thereby avoiding costly checking and repair work and at thesame time producing a knitted article without the describedirregularity.

A particularly simple arrangement is produced if the coincidence circuitcomprises two switches connected in series, one of which can be operatedby the stop motion device and the other by the signal generator. Thecontrol device which switches off the drive of the machine disconnectssaid drive whenever the two switches are simultaneously closed.

A preferred embodiment of the signal generator comprises a cam which ismoved by the machine. One of the switch positions is reached if aplunger which moves over the camis located in a section of small radius,and the other switch position is reached if said plunger is located inasection of large radius.

Other features and advantages of the invention are shown in thefollowing description of a practical embodiment with the aid of thedrawings.

FIG. 1 shows a schematic representation of a flat machine provided witha thread storage device,

FIG. 2 shows a block circuit diagram of the control device according tothe invention,

FIG. 3 shows a schematic representation of several control units of apreferred embodiment, and

FIG. 4 is a schematic representation of a modified control system.

The part of a flat machine 1 shown in FIG. 1 comprises the needle bed 2with the sliding carriage 3 mounted thereon. The carriage 3 can be movedon the needle bed and is shown in a second position by broken lines 3'.The thread F to be processed is fed to the flat machine 1 via a threadstorage device 4. The storage device 4 comprises a storage drum 5 onwhich a given quantity of thread 6 is constantly'stored. This type ofthread storage device is described in US. Pat. No. 3,606,975 in the nameof the same applicant. Mounted on a vertical pin (not shown) on thestorage device 4 is a bobbin 7 from which the thread F is unwound andfed to the storage drum 5 via thread guiding elements 8 which at thesame time form part of a conventional stop motion device. Stop motiondevices are known per se and are usually used to detect a threadbreakage. There are also known stop motion devices which are susceptibleto irregularities in the thread.

The block diagram shown in FIG. 2-inlcudes the stop motion device '9which is connected toa coincidence 3 stop motion device 9 and the signaltransmitter 10. The stop motion device 9 only transmits a signal in theevent of a located thread breakage. The signal transmitter 10 isdesigned so that it periodically transmits asignal whenever the flatmachine is in a position in which it can be easily stopped. In the caseof the flat machine shown in FIG. 1 this is the position in which thecarriage 3 is, as shown, located at its point of reversal. When a threadbreakage is located the coincidence circuit 1 1 does not thereforetransmit a signal to its output until the sliding carriage 3 has reachedthis point of reversal. The control device 12 which is connected to thecoincidence circuit 11 then causes the machine drive 13 to be stopped. Adead time which occurs between the transmission of the output signal tothe coincidence circuit 11 and the eventual stopping of the machinedrive 13 or flat machine 11 can be taken into account if the signaltransmitter 10 is controlled by the machine drive 13 with a given phasedisplacement. As shown in FIG. 3, the signal transmitter 10 is formed bya cam 19 controlled by the machine drive 13. A plunger 15 which actuatesa switch 16 moves over the circumference of the. cam. The switch 16 isclosed whenever the plunger 15 is located in the areaof the cam 19having a smaller radius. A second switch a is connected in series to theswitch 16. The series connection comprising a voltage supply 17 and arelay B is connected in parallel to these two switches. The switch a isoperated by a relay A located in the stop motion device 9. It is closedwhenever the stop motion device 9 locates a thread breakage. The closedposition of the switch 16 designates that position of the flat machine 1in which the machine can be switched off. It can be seen that currentonly flows through the relay B when the two switches 16 and'a areclosed.

Another circuit as shown in FIG. 3 shows the machine drive 13 which isconnected in parallel to the series connection comprising a voltagesupply 18 and a switch b. The switch b represents a contact of the relayB which is opened when current flows through said relay. The machinedrive 13 is therefore switched off as soon as current flows through therelay B.

A comparison between the block diagram shown in FIG. 2 and the circuitdiagrams in FIG. 3 shows that the coincidence circuit 11 corresponds tothe series connection comprising the two switches 16 and a.- The circuitcontrolling the relay B is only closed when both switches 16 and a aresimultaneously closed. The control device 12 corresponds to the relayswitch b.The

cam 19 can also be provided with a plurality of separate sections ofsmaller radius if the machine has several positions in which it can beeasily stopped. Furthermore, the two switches 16 and a may as shown inFIG. 4 be also connected in parallel, instead of in series, the positionfor switching off the machine drive being given when both switches areopen. In FIG. .4 the samereference numerals as appearing in FIG. 3 havebeen used except for the addition of a double prime thereto. Theoperation of e HQ mbpsi l i nt.is... zeh a e d sizey and thus a detaileddescription of same is not believed necessary. The control deviceaccording to the invention may be generally applied to textile machinesin which there occur intervals during movement in which it is moreadvantageous than in other intervals of movement to switch off themachine. What I claim is:

1. In a flat knitting machine having a movable carriage, a drive meansfor controlling the movement of said carriage, a control device forswitching on and off the drive means, a plurality of thread processingparts for knitting a thread, and a bobbin for supplying the thread tosaid thread processing parts, the improvement comprising a threaddelivery and control device associated with said machine for permittingat least a limited quantity of thread to be supplied to said threadprocessing parts afterbreakage of the thread as supplied from saidbobbin for permitting continued operation of said machine until saidcarriage reaches a preselect'ed position, said thread delivery andcontrol device including:

a thread storage device coacting with the thread as supplied from thebobbin to the thread processing parts for storing thereon a limitedamount of thread so that sufficient thread will be available for supply.to said thread processing parts even after breakage of the thread assupplied from the bobbin so as to enable the movable carriage of theknitting machine to continue to move until same reaches said preselectedposition, stop motion device coacting with the thread between the bobbinand the thread storage device, said stop motion device including meansassociated therewith for indicating when the thread as supplied from thebobbin to *the thread storage device is broken; signal transmittingdevice controlled by said knitting machine and movable between twodifferent control positions and occupying one of said control positionswhen the machine is in a given recurrent position in'which idling of themachine has little or no disadvantageous effect; and

coincidence circuitry means operatively connected to said control devicefor switching off the machine drive means when said coincidence deviceis activated, said coincidence device being operativelyinterconnected tosaid stop motion device and said signal transmitting device and beingactivated only when said signal transmitting device is in said onecontrol position and said stop motion device indicates a threadbreakage.

2. In a knitting machine according to claim 1; wherein thecoincidencecircuitry means includes first and second switches,-one ofsaid'switches being operatively connected to and actuated by said stopmotion device, the other switch being operatively connected to andactuated by said signal transmitting device.-

3. In a knitting machine according to claim 2,' wherein said first andsecond switches are connected in .s r qswith e ano 4. In a knittingmachine according to claim 2, wherein said signal transmitting deviceincludes a rotatable cam movable by said machine and positioned foractpating said other switch.

5. In a knitting machine according to claim 1, wherein saidthreadstorage device includes a drum having a substantially constantquantity of thread .w9 a Jh i 6. In a knitting machine according toclaim 1, wherein said preselected position comprises the point where themotion of said carriage is reversed.

ik l I l

1. In a flat knitting machine having a movable carriage, a drive meansfor controlling the movement of said carriage, a control device forswitching on and off the drive means, a plurality of thread processingparts for knitting a thread, and a bobbin for supplying the thread tosaid thread processing parts, the improvement comprising a threaddelivery and control device associated with said machine for permittingat least a limited quantity of thread to be supplied to said Threadprocessing parts after breakage of the thread as supplied from saidbobbin for permitting continued operation of said machine until saidcarriage reaches a preselected position, said thread delivery andcontrol device including: a thread storage device coacting with thethread as supplied from the bobbin to the thread processing parts forstoring thereon a limited amount of thread so that sufficient threadwill be available for supply to said thread processing parts even afterbreakage of the thread as supplied from the bobbin so as to enable themovable carriage of the knitting machine to continue to move until samereaches said preselected position; a stop motion device coacting withthe thread between the bobbin and the thread storage device, said stopmotion device including means associated therewith for indicating whenthe thread as supplied from the bobbin to the thread storage device isbroken; a signal transmitting device controlled by said knitting machineand movable between two different control positions and occupying one ofsaid control positions when the machine is in a given recurrent positionin which idling of the machine has little or no disadvantageous effect;and coincidence circuitry means operatively connected to said controldevice for switching off the machine drive means when said coincidencedevice is activated, said coincidence device being operativelyinterconnected to said stop motion device and said signal transmittingdevice and being activated only when said signal transmitting device isin said one control position and said stop motion device indicates athread breakage.
 2. In a knitting machine according to claim 1, whereinthe coincidence circuitry means includes first and second switches, oneof said switches being operatively connected to and actuated by saidstop motion device, the other switch being operatively connected to andactuated by said signal transmitting device.
 3. In a knitting machineaccording to claim 2, wherein said first and second switches areconnected in series with one another.
 4. In a knitting machine accordingto claim 2, wherein said signal transmitting device includes a rotatablecam movable by said machine and positioned for actuating said otherswitch.
 5. In a knitting machine according to claim 1, wherein saidthread storage device includes a drum having a substantially constantquantity of thread wound thereon.
 6. In a knitting machine according toclaim 1, wherein said preselected position comprises the point where themotion of said carriage is reversed.